First, you should be commended for seeking out additional information on your own.
Khan Academy has a very basic intro to cybersecurity concepts: https://www.khanacademy.org/partner-content/nova/cybersecurity
But since you are taking the class, ask the teacher what you should catch up on and study on your own. Read the textbook.
Seriously, since the course could be anything, but is probably the "Algebra 1" equivalent of cybersecurity, and we don't know what you do and don't know already, its hard to identify what you need to focus on. "Cybersecurity" is a field with many broad domains of knowledge and literally hundreds or more of skills and tasks.
For example this is based on the NIST Cyber Workforce framework. Every white box is a completely distinct career path. http://www.nist80037rmf.com/wp-content/uploads/2016/01/nist-dod-8140.jpg
So it will be hard to give you guidance that won't "blow your brains out" by being way over your head, or be so dumbed down it is useless to you.
But here are some ideas:
- Coursera has a series of free courses: https://www.coursera.org/specializations/intro-cyber-security
- Get a Security+ study guide, it's the #1 intro cert for security and you may be able to sit for it after your class(es) anyway
- Listen to the Malicious Life podcast from the beginning, it's basically an oral history of malware and cybersecurity from the 1970s forward
- Listen to Darknet Diaries podcast, it is another oral history and is very high quality and very engaging
- Learn python
- Ask questions here